Chemistry Enviromental Chemistry SLO

8/2/2019 Chemistry Enviromental Chemistry SLO

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Environmental Chemistry

Definition of Atmosphere : SLO# 14.1.1

The general name for a layer of gases that may surround a material object(Earth) is called as atmosphere.

Atmosphere Composition: SLO# 14.2.1

The earth's atmosphere near the surface is composed primarily of Nitrogen andOxygen. Together, the two comprise about 99% of the gas in the atmosphere. Thekey components of the lower atmosphere,

Nitrogen - 78.084%Oxygen - 20.95%Argon - 0.934%Carbon Dioxide - 0.036%

Neon - 0.0018%Helium - 0.0005%Methane - 0.00017%Hydrogen - 0.00005%Nitrous Oxide - 0.00003%Ozone - 0.000004%

In addition, water vapor is variable but typically makes up about 1-4% of theatmosphere

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Composition of the Atmosphere :

The oxygen is characteristic of our atmosphere was almost all produced byplants. The present composition of the atmosphere is 79% nitrogen, 20%oxygen, and 1% other gases.

Layers of the Atmosphere : SLO# 14.2The atmosphere of the Earth may be divided into several distinct layers, as

the following figure indicates.

Layers of the Earth's atmosphere

The Troposphere : Thetroposphere is where all weather takes place

It is the region of rising and falling packets of air



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The air pressure at the top of the troposphere is only 10% of that at

sea level about 0.1 atmosphere

There is a thin buffer zone between the troposphere and the next layer

called the tropopause.

The Stratosphere and Ozone Layer : Above the troposphere is the stratosphere, where air flow is mostly

horizontal.

The thin ozone layer in the upper stratosphere has a high

concentration of ozone, which is a particularly reactive form of oxygen.

This layer is primarily responsible for absorbing the ultraviolet

radiation from the Sun.

The Mesosphere and Ionosphere : Above the stratosphere is the mesosphere and above that is the

ionosphere or thermosphere, where many atoms are ionized.

The ionosphere is very thin, but it is where aurora takes place, and is

also responsible for absorbing the most energetic photons from the

Sun, and for reflecting radio waves, thereby making long-distance

radio communication possible.

The structure of the ionosphere is strongly influenced by the chargedparticle wind from the Sun (solar wind), which is in turn governed bythe level of solar activity.

Difference between Stratosphere and Troposphere: SLO #

14.2.2

Troposphere :-

It is from 0 to 15 kilometers.

It has more air and has many clouds.

Stratosphere

It is from 15 km to 50 km.

It has very little air and jet aero planes fly in this layer



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Components of Stratosphere & Troposphere SLO # 14.2.3

Components of troposphere:1. Gases.

2. Vapors.

3. Clouds.

4. Dust particles.

Components of stratosphere:1. Traces of gases

2. Ozone layer

3. Gravity waves

4. Bacteria

The Troposphere :

Troposphere means, where the air turns over.

A very appropriate name, since the air closest to the earth is in aconstant up and down flow. Also in this layer, the air is hotter closer tothe earths surface and colder the higher up you travel.

The troposphere is immediately important in our daily activities.

Starting at sea level, the troposphere goes up seven miles. The bottomone third, that which is closest to us, contains 50% of all atmosphericgases.

This is the only part of the whole makeup of the atmosphere that isbreathable.

This is the only area where all weather takes place. It also has theproperty of having a north south oriented aspect.

Next, is a thin layer called the tropopause, which is just a bufferbetween the troposphere and the stratosphere

The Stratosphere :

The stratosphere is the next layer of the atmosphere.



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Here the air doesnt flow up and down, but flows parallel to the earth invery fast moving air streams.

This is the layer where most jet planes fly.

The stratosphere starts at approximately 10 kilometers and goes toapproximately fifty kilometers high.

The top edge of the stratosphere is abundant with ozone.

Ozone is the byproduct of sun radiation and oxygen; by capturing theultraviolet rays of the sun and deploying it, ozone takes out theharmful effects. This is very important to all living things on earth,since unfiltered radiation from the sun can destroy all animal tissue.

After the stratosphere, there is again a buffer layer, this time called

the stratopause



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Mesosphere :

The mesosphere (50 - 85 km) is characterized by a continuousdecrease of temperature.

It reaches it minimum with almost -100 C at about 80 km of height.

This also is the upper boundary of the mesosphere.

Thermosphere :

In the thermosphere (85 - 500 km) no temperatures but only

emittances may be measured because of the very low density ofparticles.

Exosphere :

The exosphere (> 500 km) starts depending on definition at500 - 1000 km of height.

Here, pressure is so low that it can already be called vacuum.

Major Air Pollutants SLO # 14.3.1Air pollution is a real public health and environmental problem that can lead toamong otherthingsglobal warming, acid rain, and the deterioration of the ozone layer.

This chart names some common pollutants, their sources, and their effect on the environment.

Pollutant Sources Effects



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Ozone.

A gas that can be found in

two places. Near the

ground (the troposphere),

it is a major part of smog.

The harmful ozone in the

lower atmosphere should

not be confused with the

protective layer of ozonein the upper atmosphere

(stratosphere), which

screens out harmful

ultraviolet rays.

Ozone is not created

directly, but is formed

when nitrogen oxides

and volatile organic

compounds mix in

sunlight. That is why

ozone is mostly found

in the summer.

Nitrogen oxides come

from burning gasoline,

coal, or other fossil

fuels. There are manytypes of volatile

organic compounds,

and they come from

sources ranging from

factories to trees.

Ozone near the ground

can cause a number of

health problems.

Ozone can lead to

more frequent asthma

attacks in people who

have asthma and can

cause sore throats,

coughs, and breathing

difficulty. It may even

lead to premature

death. Ozone can alsohurt plants and crops.



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Carbon

monoxide.

A gas that comes from the

burning of fossil fuels,

mostly in cars. It cannot

be seen or smelled.

Carbon monoxide is

released when engines

burn fossil fuels.

Emissions are higher

when engines are not

tuned properly, and

when fuel is not

completely burned.

Cars emit a lot of the

carbon monoxide found

outdoors. Furnaces and

heaters in the homecan emit high

concentrations of

carbon monoxide, too,

if they are not properly

maintained.

Carbon monoxide

makes it hard for body

parts to get the oxygen

they need to run

correctly. Exposure to

carbon monoxide

makes people feel

dizzy and tired and

gives them headaches.

In high concentrations

it is fatal. Elderly

people with heartdisease are

hospitalized more often

when they are exposed

to higher amounts of

carbon monoxide.

Nitrogen

dioxide.

A reddish-brown gas that

comes from the burning of

fossil fuels. It has a strong

smell at high levels.

Nitrogen dioxide

mostly comes from

power plants and cars.

Nitrogen dioxide isformed in two ways

when nitrogen in the

fuel is burned, or when

nitrogen in the air

reacts with oxygen at

very high

temperatures. Nitrogen

dioxide can also react

in the atmosphere to

form ozone, acid rain,

and particles.

High levels of nitrogen

dioxide exposure can

give people coughs

and can make themfeel short of breath.

People who are

exposed to nitrogen

dioxide for a long time

have a higher chance

of getting respiratory

infections. Nitrogen

dioxide reacts in the

atmosphere to form

acid rain, which can

harm plants and

animals.



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Particulate

matter.

Solid or liquid matter that

is suspended in the air. To

remain in the air, particles

usually must be less than

0.1-mm wide and can be

as small as 0.00005 mm.

Particulate matter can

be divided into two

typescoarse particles

and fine particles.

Coarse particles are

formed from sources

like road dust, sea

spray, and

construction. Fine

particles are formed

when fuel is burned in

automobiles and powerplants.

Particulate matter that

is small enough can

enter the lungs and

cause health problems.

Some of these

problems include more

frequent asthma

attacks, respiratory

problems, and

premature death.

Sulph ur

dioxide.

A corrosive gas that

cannot be seen or smelled

at low levels but can have

a rotten egg smell at

high levels.

Sulfur dioxide mostly

comes from the

burning of coal or oil in

power plants. It also

comes from factories

that make chemicals,

paper, or fuel. Like

nitrogen dioxide, sulfurdioxide reacts in the

atmosphere to form

acid rain and particles.

Sulfur dioxide exposure

can affect people who

have asthma or

emphysema by making

it more difficult for

them to breathe. It can

also irritate people's

eyes, noses, andthroats. Sulfur dioxide

can harm trees and

crops, damage

buildings, and make it

harder for people to

see long distances.

Lead.

A blue-gray metal that isvery toxic and is found in

a number of forms and

locations.

Outside, lead comes

from cars in areas

where unleadedgasoline is not used.

Lead can also come

from power plants and

other industrial

High amounts of lead

can be dangerous for

small children and canlead to lower IQs and

kidney problems. For

adults, exposure to

lead can increase thewww.tec.edu.pk [email protected]

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sources. Inside, lead

paint is an important

source of lead,

especially in houses

where paint is peeling.

Lead in old pipes can

also be a source of

lead in drinking water.

chance of having heart

attacks or strokes.

Toxic air

pollutants.

A large number of

chemicals that are known

or suspected to cause

cancer. Some important

pollutants in this category

include arsenic, asbestos,

benzene, and dioxin.

Each toxic air pollutant

comes from a slightly

different source, but

many are created in

chemical plants or are

emitted when fossil

fuels are burned. Some

toxic air pollutants, like

asbestos and

formaldehyde, can be

found in building

materials and can lead

to indoor air problems.Many toxic air

pollutants can also

enter the food and

water supplies.

Toxic air pollutants can

cause cancer. Some

toxic air pollutants can

also cause birth

defects. Other effects

depend on the

pollutant, but can

include skin and eye

irritation and breathing

problems.

Stratospheric

ozone

depleters :

Chemicals that can

destroy the ozone in the

CFCs are used in air

conditioners and

refrigerators, since

they work well as

coolants. They can alsobe found in aerosol

cans and fire

extinguishers. Other

stratospheric ozone

If the ozone in the

stratosphere is

destroyed, people are

exposed to more

radiation from the sun(ultraviolet radiation).

This can lead to skin

cancer and eye

problems. Higherwww.tec.edu.pk [email protected]

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stratosphere. These

chemicals include

chlorofluorocarbons

(CFCs), halogens, and

other compounds that

include chlorine or

bromine.

depleters are used as

solvents in industry.

ultraviolet radiation

can also harm plants

and animals.

Greenhouse

gases.

Gases that stay in the air

for a long time and warm

up the planet by trapping

sunlight. This is called the

greenhouse effect

because the gases act like

the glass in a greenhouse.

Some of the important

greenhouse gases arecarbon dioxide, methane,

and nitrous oxide.

Carbon dioxide is the

most important

greenhouse gas. It

comes from the

burning of fossil fuels

in cars, power plants,

houses, and industry.

Methane is released

during the processing

of fossil fuels, and also

comes from natural

sources like cows and

rice paddies. Nitrous

oxide comes fromindustrial sources and

decaying plants.

The greenhouse effect

can lead to changes in

the climate of the

planet. Some of these

changes might include

more temperature

extremes, higher sea

levels, changes in

forest composition, and

damage to land near

the coast. Human

health might be

affected by diseases

that are related totemperature or by

damage to land and

water.

Air Pollution FactsheetAir pollution consists of substances present in the atmosphere in highenough levels to harm humans, other animals, plants, or materials. Airpollution can result from human activities such as driving cars. It can alsocome from natural sources, such as smoke from forest fires caused bylightning or from volcano eruptions.

The story so far:Pollution caused by humans is now disturbing the delicatebalance of nature on earth. Far from being a new problem, pollution has



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been around for centuries. However, as the population increases, pollutionproblems also increase. A combination of a rapidly multiplying population,

and the growth of industries and car use are the main causes of air pollutiontoday.

Major Air Pollutants & their Impacts :Suspended Particulate Matter:

This is a mixture of solid and liquid particles suspended in the air. Suspendedparticulates are seen as dust, smoke, and haze which can make breathing difficult,especially for people with chronic respiratory problems.

Volatile Organic Compounds :VOCs include gasoline, paint solvents, and organic cleaning solutions. Theyevaporate and enter the air as vapour, and as molecules resulting from theincomplete burning of fuels and wastes.

Carbon Monoxide :One source of carbon monoxide is vehicle emissions. This is an invisible,odourless gas that is highly toxic to air-breathing animals because itinterferes with the blood's ability to transport oxygen. Even low levels canstart or increase damage to the heart in individuals with artery or heartproblems. At medium concentrations, carbon monoxide causes headaches

and fatigue. As the concentration increases, reflexes slow down anddrowsiness occurs. At high levels carbon monoxide causes death. People atgreatest risk from carbon monoxide include pregnant women, infants, andthose with heart or respiratory diseases.

Nitrogen Oxides :Nitrogen Oxides are lung irritants that can lead to acute respiratory diseasesin children. They may also cause over-sensitivity to pollen and dust in peoplesuffering from asthma.

Sulphur Oxides :Sulphur Dioxide is converted to sulphuric acid in the atmosphere. It can bepoisonous to both plants and animals. Like particulates, sulphur dioxideirritates the respiratory tract, causing airways to close, and interfering withthe lungs. Children and the elderly are especially sensitive to sulphur



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dioxide, as are people suffering from asthma and emphysema.

Lead & other heavy metals:Lead is dangerous, even at low concentrations and can lead to reducedintelligence in children, brain damage and death. It accumulates in the bodyand damages body tissue.

Ground Level Ozone :Ozone in the upper atmosphere shields us from ultraviolet radiation.However on ground level, it is highly toxic to both plants and animals as itcan damage lungs. It can bring on coughing; asthma attacks and lowers theimmune system.

Fuel wood:Indoor air pollution is caused by the burning of fuel-wood and dung forcooking, and can cause suffocation.

Sources of Air pollution :

Motor vehicles :Two main sources of air pollution are motor vehicles & industries. When theyburn petrol, cars and trucks release significant quantities of sulphur dioxide,oxides of nitrogen, carbon monoxide, lead, and suspended particulatematter. Lead used in petrol to protect engines is also dangerous. Diesel

powered cars produce large quantities of particulates in the form of blacksoot. Reduced use of private cars, proper legislation and enforcement of lawscan curb this menace.

Industry:Electrical power plants and industries emit particulate matter, sulphuroxides, nitrogen oxides, hydrocarbons and carbon dioxides.The top three industrial sources of toxic air pollutants are the chemical,metal, and paper industries.

Municipal Solid Waste:

When solid waste is burnt, heavy metals like lead, gases and soot are spreadover residential areas. Rubbish, dust and gases found during thedecomposition of waste, all contribute to air pollution.



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Smog :

when air pollution in urban areas reduces visibility it is often called smog.There are different types of smog. Smoke pollution from industries issometimes called industrial smog. The pollutants it contains are sulphuroxides and particulates. Photochemical smog is a brownish orange hazeformed by chemical reactions involving sunlight.

Medical waste:

Burning medical waste is a serious source of air pollution, particularly incities. Most incinerators are rudimentary by today's standards. They burn

waste incompletely, releasing acidic gases, heavy metals, and dioxins intothe air.

Developing countries:

As developing countries become more industrialized, they also produce moreair pollution. The leaders of most developing countries believe they mustbecome industrialized rapidly in order to be economically competitive.Environmental quality is usually a low priority in the race to develop. Thus,while air quality is slowly improving in developed countries, it is rapidlydeteriorating in developing countries.

Improving the well being of developing nations does not have to result inincreased pollution. The key to future development lies in providing theproducts and services which people want by using the most efficienttechnologies, and consuming the lowest possible level of resources.

A ir pollution affect:Exposure to low levels of pollutants such as ozone, sulphur oxides, nitrogenoxides, and particulates, irritates eyes and causes inflammation of therespiratory tract. Evidence exists that many air pollutants also suppress theimmune system, increasing susceptibility to infection. In addition, evidencecontinues to accumulate indicating that exposure to air pollution during

respiratory illnesses may result in people developing chronic respiratorydiseases, such as emphysema and bronchitis as they get older. Other healthproblems that can result from long-term exposure to toxic air-pollutants arecancer, chronic obstructive pulmonary disease, asthma, respiratoryinfections, and cardiovascular disease.



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Air pollution can also cause acidification of lakes and soils and impacts oncrop productivity, forest growth, and biodiversity. Some research indicates

that the ozone and sulphur dioxide is reducing crop yields. The potential forcrop losses in Asia has been indicated by a study in Pakistan where a 40 percent reduction in rice yields was linked to the presence of pollutants in theair.

Role of Government & Society to control pollution: SLO#14.3.4

Encourage people to leave their car at home and walk or ride a bicycleto travel short distances.

Develop efficient public transport systems to help reduce dependenceon private cars.

Provide Government subsidies to encourage the introduction of petrolwith low sulphur and no lead.

Focus on regional inter-Governmental cooperation. Pollutants can becarried from one country to another, so individual countries cannotsolve the associated problems alone.

Promote energy efficiency and conservation. Energy efficiency meansusing technology to accomplish tasks with less energy. Energyconservation focuses on cutting down on wasteful energy consumingactivities.

Effective ways of reducing harmful emissions from industries andvehicles, but they also give us time to search for safer and cheaperalternative energy sources.

Use smaller, more efficient cars as they consume less fuel and soproduce fewer emissions.

Design cars so that combustion temperatures are lower and lessnitrogen oxide is formed. Use lighter materials and better designedcars.



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Find better alternative fuels, as petroleum reserves will not last for

ever. Alcohol, solar power, electricity and liquid hydrogen are some of the

options that car manufacturers have investigated in the search foralternative fuels.

All alternative fuels will not necessary be environmentally friendly. Forinstance, if the electricity for electricity-powered cars is produced bycoal-fired power plants, the eventual volume of emissions will behigher than for conventionally fuelled cars.Fit smoke-stacks with electrostatic precipitators, fabric filters,scrubbers, or other technologies to remove particulate matter.

Use careful land-excavating methods to control particulates. Forexample, water can be sprinkled on dry soil that is being moved duringroad construction.

Remove sulphur dioxide from fuel by switching to a low-sulphur fuelsuch as natural gas or even to a non-fossil source such as solar energy.

Modify furnaces and engines to provide more complete combustion.This helps control the production of both carbon monoxide andhydrocarbons.

Dynamical mechanismsThere are several possible dynamical mechanisms by which the stratospheremight affect the troposphere.

There are two aspects to this:

(a) how information might be communicated in the vertical and

(b) why the tropospheric response might be larger than expected.



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Schematic diagram indicating the role of different aspects of the dynamics inthe dynamical mechanisms discussed in the text. Note that dynamics ofmean circulation includes non-local PV inversion (or equivalently the short-time effect of the meridional circulation) and the effect of the meridionalcirculation on longer time scales, including the downward control limit.

Waste Incineration - An Effective Waste Management

Process : SLO# 14.3.3

Environment has great influence in the life of all the living things on thisearth. When it comes to wastage and its treatment, one of the very oldesteffective waste treatments is waste incineration. It is basically a process



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where the domestic and industry waste materials are burnt. In this process,the waste materials turn into ash, flue gas and heat. On the basis of the type

of waste materials, the incineration can of various scales, such as: smallscale, medium scale and large scale.

Though some people think that waste management or waste treatment isnot a very big issue, but in reality it is a serious matter of concern. In wasteincineration method, waste materials or organic substances are burnt whichincorporate households, hazardous and also medical wastes equipments. Asthe method of incineration involves combustion, therefore it is also known asthermal treatment. These days, the incinerations help in saves energy frombeing wasted.

Moreover, the method of incineration has a lot of benefits over other types ofwaste treatment system. While treating the waste materials, such as clinicaland hazardous materials, waste incineration has proved to be more effectivein this regard. By using this waste treatment method, the harmful pollutantand pathogens can be burnt completely in high temperature. This method ofwaste treatment has become extremely popular in countries having scarcityof lands.



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However, while gong for waste incineration, one should also keep in mindthat this process can have some negative effectives on our health due toenvironmental pollution. Production of ashes, flue gases and other releasesof incineration can also lead to some serious consequences on mankind aswell as on our natural atmosphere. In incineration, the waste materials getreduced in its amount and also get transformed into ashes that consist ofsome of the most venomous substances like: dioxins and heavy metals.

These substances are difficult to destroy.

As we all know that waste materials can be of various kinds, therefore inorder to manage various kinds of waste materials, various types ofincinerator plants are designed, such as: moving grate, fixed grate, rotary-kiln, and fluidized bed. The best thing about the modern incinerators is thatthey have pollution mitigation equipment such as flue gas cleaning in them.


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